/*
 * Copyright (c) 2003, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
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 */
package com.sun.corba.se.spi.monitoring;

import java.util.*;

/**
 * <p>
 *
 * @author Hemanth Puttaswamy
 * </p>
 * <p>
 * StatisticsMonitoredAttribute is provided as a convenience to collect the
 * Statistics of any entity. The getValue() call will be delegated to the
 * StatisticsAccumulator set by the user.
 * </p>
 */
public class StatisticMonitoredAttribute extends MonitoredAttributeBase {

    // Every StatisticMonitoredAttribute will have a StatisticAccumulator. User
    // will use Statisticsaccumulator to accumulate the samples associated with
    // this Monitored Attribute
    private StatisticsAccumulator statisticsAccumulator;

    // Mutex is passed from the user class which is providing the sample values.
    // getValue() and clearState() is synchronized on this user provided mutex
    private Object mutex;

    ///////////////////////////////////////
    // operations

    /**
     * <p>
     * Constructs the StaisticMonitoredAttribute, builds the required
     * MonitoredAttributeInfo with Long as the class type and is always
     * readonly attribute.
     * </p>
     * <p>
     *
     * @param name Of this attribute
     * </p>
     * <p>
     * @return a StatisticMonitoredAttribute
     * </p>
     * <p>
     * @param desc should provide a good description on the kind of statistics
     * collected, a good example is "Connection Response Time Stats will Provide the
     * detailed stats based on the samples provided from every request completion
     * time"
     * </p>
     * <p>
     * @param s is the StatisticsAcumulator that user will use to accumulate the
     * samples and this Attribute Object will get the computed statistics values
     * from.
     * </p>
     * <p>
     * @param mutex using which clearState() and getValue() calls need to be locked.
     * </p>
     */
    public StatisticMonitoredAttribute(String name, String desc, StatisticsAccumulator s, Object mutex) {
        super(name);
        MonitoredAttributeInfoFactory f = MonitoringFactories.getMonitoredAttributeInfoFactory();
        MonitoredAttributeInfo maInfo = f.createMonitoredAttributeInfo(desc, String.class, false, true);

        this.setMonitoredAttributeInfo(maInfo);
        this.statisticsAccumulator = s;
        this.mutex = mutex;
    } // end StatisticMonitoredAttribute

    /**
     *  Gets the value from the StatisticsAccumulator, the value will be a formatted
     *  String with the computed statistics based on the samples accumulated in the
     *  Statistics Accumulator.
     */
    public Object getValue() {
        synchronized (mutex) {
            return statisticsAccumulator.getValue();
        }
    }

    /**
     *  Clears the state on Statistics Accumulator, After this call all samples are
     *  treated fresh and the old sample computations are disregarded.
     */
    public void clearState() {
        synchronized (mutex) {
            statisticsAccumulator.clearState();
        }
    }

    /**
     *  Gets the statistics accumulator associated with StatisticMonitoredAttribute.
     *  Usually, the user don't need to use this method as they can keep the handle
     *  to Accumulator to collect the samples.
     */
    public StatisticsAccumulator getStatisticsAccumulator() {
        return statisticsAccumulator;
    }
} // end StatisticMonitoredAttribute
